Mini Brittle Star Mass Die Off

[ScubaSteve]

So, weird thing is happening today. This morning I saw a mini brittle star lying wrong side up on the sand by a rock. Didn't think too much of it, sometimes they do weird things. Got home after work and there were a couple on the sand and a few on the rocks looking pretty lifeless. I pulled one of them out to check it out and at first it didn't move... but then it twitched just the end of one of its arms. Alive, but barely.

I am now looking in the tank late tonight and I can see at least a dozen of the little guys, some on the sand, some on the rocks, some half out of holes. It honestly looks like a battlefield of corpses. I don't know about you, but this worries me. I see this as a canary in the coal mine.

The only thing that I had done different this week is that I have been raising my mag slowly using magnesium sulphate. It was low last weekend at 1050 ppm and I've been slowly raising it over the past 5 days by no more than 80 ppm per day. I checked my salinity and found that it had gone up to 1.028 from 1.026 last weekend; I am attributing this raise in salinity to adding ~750g of magnesium sulphate (epsom salts) in order to raise the mag. I'll be lowering the salinity slowly over the next week or two. I added the mag slowly; added a bit on Sunday to see how things went and then slowly added more to get to 1400 ppm over the next few days.

The other strange thing that has happened recently is in my strawberry top snail. He is still alive, but like the brittle stars, barely. He's tucked unto his shell but not all the way; his foot is still sticking out. Sniff test and a poke to the foot tells me he's still alive, so he stays for now. But he otherwise looks pretty lifeless. I've seen him do this once before (so I'm not all that worried) and it was after a tank swap when the magnesium was also low. This was my first indicator that my mag was low. Test kit (Elos) confirmed this. Mag dosing commenced (slowly)

Parameters:
Alk: 9 dKH
Cal: 430 ppm
Mg: 1450 ppm
pH: 8.0
SG: 1.028

Ammonia: 0
Nitrite: 0
Nitrate: <5 ppm (it actually reads 0 ppm but I never trust it to ACTUALLY be 0 ppm)
Phosphate: <0.25 ppm (again, says 0 ppm but I don't trust it)

The tank was swapped 1.5 months ago to the new system. Something went weird in the transfer and it cycled. Hard. I lost all but a handful of my SPS (expensive frags went to a friend's tank). So I don't know if these weird happenings are part of the ensuing aftermath of the tank swap or if there is something seriously bad about to happen. I'm waiting for a small cycle if these brittle stars are dead.

[daniella3d]

Do you have sand? is it old sand or new sand?

I have used epsom salt before to try to cure a popeye on my trigger fish and I went a bit overboard and put quite a bit directly to my nano tank and it did not kill any starfish that I could see...nothing seamed to be affected from what I remember.

I would be more worried of some anaerobic area in the sand if there is sand and if the old sand was kept and moved.

Beside that, they are pretty tough little guys so this is not a good sign. I never saw one die unless it was killed by a fish or by mistake while handling frag. I even put a few in peroxyde dip without realizing it and after a few seconds in the dip they went right back into the tank and survived.

I would recommand also doing a copper test, just in case.

Do you use a well calibrated refractometer to mesure salinity or an hydrometer?



The tank was swapped 1.5 months ago to the new system. Something went weird in the transfer and it cycled. Hard. I lost all but a handful of my SPS (expensive frags went to a friend's tank). So I don't know if these weird happenings are part of the ensuing aftermath of the tank swap or if there is something seriously bad about to happen. I'm waiting for a small cycle if these brittle stars are dead.

[ScubaSteve]

I use the refractometer in my lab to do checks and I've also calibrated my swing arm hydrometer against the lab refractometer (repeatability is excellent) for doing quick check ups. The lab refractometer is calibrated daily.

I did a copper test earlier in the week with my HPLC. Aside from a little signal noise, it was undetectable. I actually use the HPLC for an elemental analysis to save on having a bunch of test kits. Waaaaay cheaper. Well, way cheaper when you have free unlimited access to a $100K HPLC :razz:

My new sand bed is a mix of new sand (actually old sand that was dried out and rinsed like no tomorrow) and a few scoops of sand from the old tank to help seed it. I can say with almost certainly that there is no excess of anaerobic activity. I have other critters that are far more sensitive to H2S and they are happy as clams (er... sorry for the pun).

Magnesium sulphate is used as a muscle relaxant for snails to anesthetize them before dissection, I don't know if it has the same effect on brittle stars though. I don't think this is the cause though because my strawberry top snail was acting funny before this.

[Delphinus]

I don't know if it's the cause but 1.028 is way too high. That's something I've never really understood. Mg obviously affects SG but so do a lot of things so 1.025 from a salt mix and then whatever Mg added to bring Mg in check to that brings up SG, but if it was say 1.025 plus Mg to get 1.028 is that equivalent to simply mixing more salt to get 1.028? More than likely not. So I can't even speculate if that's the cause here. Maybe??

The few things I can think of on top of what you have already looked for:

- copper (take a sample to an LFS maybe and ask them to do it)
- temperature swing
- O2 deprivation (likely not -- usually fish will go first if that were the case -- but, something to think about nonetheless)
- some other kind of toxicity to the tank. Detergent, soap, ..

Or it could just be a small enough ammonia cycle and the test kit just didn't catch it (it happens)..

Good luck sorting it out!!

[Xenoch88]

ANOTHER CHEMIST!!! YAY!!!!!

[ScubaSteve]

ANOTHER CHEMIST!!! YAY!!!!!

Sssshhhhhh! Those aren't the things you admit in public :razz: Actually, chemical engineer, but close enough.

[AquaticFinatic]

I just set my tank up around a month ago and did a small amount of rock transfer from my holding tank. After the rock was in I started to notice my brittle stars coming out the rock and falling to the sand dead. I had done a cycle and all was normal. The only thing that I think it might have been was when I glued my plumbing together I didn't leave it long enough to dry before I put water through them. Have you done anything like this?